Concentration vs Pressure

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Isaias Gomez D3A
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Concentration vs Pressure

Postby Isaias Gomez D3A » Sun Jan 10, 2021 9:02 pm

Conceptually, are concentration and pressure basically the same thing, just for different states? Pressure is just used for gas, but they are the same when calculating?

Rich Luong 1D
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Re: Concentration vs Pressure

Postby Rich Luong 1D » Sun Jan 10, 2021 9:06 pm

If you're dealing with concentrations and pressures in their own respective problems, then yes, they should basically function the same mathematically. However, if you need to convert pressure to concentration and vice versa, then the values won't be the same.

Jeffrey Hablewitz 2I
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Re: Concentration vs Pressure

Postby Jeffrey Hablewitz 2I » Sun Jan 10, 2021 9:09 pm

Concentration is moles of solute per volume, represented mathematically as n/V. Pressure is related to concentration but also factors in the temperature of the system. This relationship is seen in the ideal gas law, where P ∝ T*(n/V).

Jeffrey Hablewitz 2I
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Re: Concentration vs Pressure

Postby Jeffrey Hablewitz 2I » Sun Jan 10, 2021 9:09 pm

Concentration is moles of solute per volume, represented mathematically as n/V. Pressure is related to concentration but also factors in the temperature of the system. This relationship is seen in the ideal gas law, where P ∝ T*(n/V).

JoshMoore2B
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Re: Concentration vs Pressure

Postby JoshMoore2B » Sun Jan 10, 2021 9:10 pm

Isaias Gomez D3A wrote:Conceptually, are concentration and pressure basically the same thing, just for different states? Pressure is just used for gas, but they are the same when calculating?


Not necessarily. With PV = nRT, we can see that pressure is dependent on a few things beyond just moles, whereas concentration is based purely on moles. As for using partial pressures for calculations with equilibrium, the relative partial pressures should be the same as the relative concentrations, I believe. However, as for calculations, they can be very similar.

Gina Spagarino 3G
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Re: Concentration vs Pressure

Postby Gina Spagarino 3G » Sun Jan 10, 2021 9:30 pm

simplifying the n/v in the equations, P=(conc)RT which shows clearly where to plug in a given molarity

kristinalaudis3e
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Re: Concentration vs Pressure

Postby kristinalaudis3e » Sun Jan 10, 2021 10:17 pm

when calculating, yes they are the same mathematically, but conceptually they are different. concentration is solely based on moles whereas partial pressures are related to temperatures and moles

David Liu 1E
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Re: Concentration vs Pressure

Postby David Liu 1E » Sun Jan 10, 2021 10:18 pm

for the questions that we've discussed, I think that they mean the same thing for calculations (though it'll get harder and we'd need to know the difference later)

Jaden Kwon 3C
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Re: Concentration vs Pressure

Postby Jaden Kwon 3C » Sun Jan 10, 2021 10:23 pm

I think mathematically they follow the same process when calculating K, but conceptually Kc is defined by molar concentrations while Kp is defined using partial pressures of gasses.

Joshua_Chan_3K
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Re: Concentration vs Pressure

Postby Joshua_Chan_3K » Sun Jan 10, 2021 10:24 pm

I think the reason you are asking this is because the chemical equilibrium equation can be calculated with both concentration and pressure through the same method. The reason why this is possible is because concentration and pressure are fixed to each other based on different temperatures. Since you can assume that gasses mixing in a reaction will both be the same temperature, it is easy to use pressure instead of concentration in the equation since the concentrations are only being measured relative to each other. Another way to think about it is that if you substitute the concentration in the equation with the pressure using the ideal gas law (or one of the smaller derivatives) all the variables will cancel out and you will be left with pressure.


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